1. Field of the Invention
The present invention relates to a new and improved airbag inflator having a filter of varying permeability. More particularly, the present invention is concerned with a new and improved varying permeability filter for use in an airbag inflator for insuring that undesirable by-products and contaminants are filtered out and entrapped during inflation of the airbag.
2. Background of the Prior Art
One of the problems associated with airbag inflators is caused because the rapid generation of hot gases expanding and moving through a filter sometimes results in burn holes or blow out of the filter in a region closely adjacent to the diffuser outlet holes in the housing of the inflator and efficient filtering action suffers. Because the diffuser holes in many inflator housings are spaced closer to one edge of the housing than the other, the gas that is generated in the region directly opposite a ring of diffuser holes has a more direct flow path through the filter and this causes the filter to experience less gas flow through regions in the filter spaced farther away from the holes. In such cases, the filter is not able to efficiently entrap contaminants and cool the gas as well as if the flow through the filter was more uniform and even across the entire available flow cross-section of the filter media.